mirror of
https://github.com/jart/cosmopolitan.git
synced 2025-02-07 23:13:34 +00:00
ec2cb88058
- Document more compiler flags - Expose new __print_maps() api - Better overflow checking in mmap() - Improve the shell example somewhat - Fix minor runtime bugs regarding stacks - Make kill() on fork()+execve()'d children work - Support CLONE_CHILD_CLEARTID for proper joining - Fix recent possible deadlock regression with --ftrace
71 lines
2.9 KiB
ArmAsm
71 lines
2.9 KiB
ArmAsm
/*-*- mode:unix-assembly; indent-tabs-mode:t; tab-width:8; coding:utf-8 -*-│
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│vi: set et ft=asm ts=8 tw=8 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2022 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/macros.internal.h"
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#define LOCK 0x2c /* see struct file in stdio.h */
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// Wrapper for applying locking to stdio functions.
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//
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// This function is intended to be called by thunks.
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//
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// @param rax has the delegate function pointer
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// @param rdi is passed along as an arg
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// @param rsi is passed along as an arg
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// @param rdx is passed along as an arg
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// @param rcx is passed along as an arg
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// @param r8 is passed along as an arg
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// @param r9 is passed along as an arg
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// @param r10 is passed along as an arg
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// @param r11 has the FILE* obj pointer
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// @return rax is passed along as result
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// @return rdx is passed along as result
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stdio_unlock:
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push %rbp
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mov %rsp,%rbp
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.profilable
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// acquires mutex
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push %rcx
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push %rdx
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mov $1,%cl
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0: mov LOCK(%r11),%dl # optimistic
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test %dl,%dl
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je 2f
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1: pause # hyperyield
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jmp 0b
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2: mov %ecx,%edx
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xchg LOCK(%r11),%dl # locks bus!
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test %dl,%dl
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jne 1b
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pop %rdx
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pop %rcx
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// calls delegate
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push %rsi
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push %r11
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call *%rax
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pop %r11
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pop %rsi
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// releases mutex
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movb $0,LOCK(%r11)
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pop %rbp
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ret
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.endfn stdio_unlock,globl
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